Annular blowout preventer

ABSTRACT

An annular blowout preventer having a resilient sealing ring with an inner bore through which well tools and the like may pass when the sealing ring is in the open position and which is compressible to smaller diameters for packing off around a drill string or the like, or even to fully close the bore, wherein the sealing ring is molded or is otherwise connected with confining upper and lower wedge members, and is actuated by an inflatable bag preferably having rigid confining strips which bridge the longitudinal distance from the upper to the lower wedges, whereby the sealing ring is substantially fully confined except at the sealing area of its inner bore.

United States Patent Watts 1 June 5, 1973 [54] ANNULAR BLOWOUT PREVENTER Primary Examiner-Martin P. Schwadron hD.Wtt,H t ,T. [75] inventor n a 5 Gus on ex Assistant Examiner-Rmhard Gerard [73] Assignee: Hydril Company, Houston, Tex. Att0rney-Pravel, Wilson & Matthews [22] Flled: June 28, 1971 [57] ABSTRACT [2]] Appl 157466 An annular blowout preventer having a resilient sealing ring with an inner bore through which well tools 52 us. Cl. ..2s1/1, 251/5, 277/343, and the like y p when the Sealing ring is in the 277/235 R open position and which is compressible to smaller [51] int. CI ..E2lb 33/06, Fl6k 7/07 diameters for p eking ff around a drill string or the [58] Field of Search ..251/1 5- 277/34 the We, the

5 235 ing ring is molded or is otherwise connected with confining upper and lower wedge members, and is actuated by an inflatable bag preferably having rigid con- [56] References cted fining strips which bridge the longitudinal distance UNITED STATES PATENTS from the upper to the lower wedges, whereby the seal- 0 ing ring is substantially fully confined except at the 1,772,210 3 193 Dale ..277 34 x sealing area f its inner bow 2,609,836 9/1952 Kn0x ..277/73 3,481,610 12/1969 Slator ..25l/5 X 3 Claims, 4 Drawing Figures 42A /2A /2 .3 i Z! V A: 5

1 J l -1 I J 1 /5 L i v I 304 /5 27 27 d/JA 5 I l 4:: .30

i M n PATENTEDJUH 5 I975 3,737,139 SHEET 2 BF 2 INVENTO lane! Y M 14 TTORN ANNULAR BLOWOUT PREVENTER BACKGROUND OF THE INVENTION The field of this invention is blowout preventers for oil wells and the like.

Annular blowout preventers made by the Hydril Company, an example of which is shown on page 2,742 of the Composite Catalog for 1970-71, have been in extensive commercial use for a number of years. Such blowout preventers provide a fully-open bore therethrough so that drill bits, reamers, casing hangers and other large diameter tools can freely pass therethrough, but when actuated to the closed position, such preventers are forced inwardly to reduce its bore and autom atically adjust its size and shape in sealing contact with whatever object happens to then be in the bore of the preventer, thereby closing off the annular space around such object to prevent a blowout of the well pressure from below. If no tool is in the well, the bore of the preventer can be fully closed to prevent a blowout.

Such prior blowout preventers have been actuated by a vertically moving piston means which has a wedge for creating inward radial movement of the resilient ring of the preventer upon vertical movement of the piston means. By reason of such prior construction, the height of the preventer is relatively great as compared to the height of the resilient packing ring itself, which sometimes limits its use, or makes installation difficult when vertical space is limited.

SUMMARY OF THE INVENTION The present invention relates to an annular blowout preventer of the Hydril type, but which is relatively inexpensive to manufacture due to the relatively few parts and the minimum amount of machining required. Also, the present preventer is relatively short in height as compared to such prior Hydril preventers, while at the same time it can accomplish the same blowout preventer functions as the prior Hydril type preventers. The preventer of this invention has a resilient packing or sealing ring which is confined above and below by segmental metal or other rigid retainer elements to prevent upward or downward extrusion of the rubber or other material forming the packing or sealing ring when the ring is urged radially inwardly to a sealing position. The outer portion of the seal ring is also confined by an inflatable bag, preferably having substantially vertical rigid retainer members therewith, which prevents outward extrusion of the sealing ring when it is urged inwardly by pressure in the inflatable bag. The upper wedge members are interlocked with each other with suitable lug means and the lower wedge members are likewise interlocked with each other to prevent a twisting or turning thereof. Also, the lugs prevent an unequal advance of the adjacent wedge members during inward and outward radial movement of such members. Further, the wedge members are engaged by the substantially vertical rigid retainer members in the bag spanning the vertical distance between such upper and lower wedge members to further assure the outward confinement of the sealing ring when it is being urged inwardly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation, partly in section, illustrating the preferred form of the annular blowout preventer of this invention with the bore thereof in the fully open position, and with a tubing string extending through the DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, the letter B designates generally the blowout preventer of this invention which includes a housing H made of steel or other suitable material and which is adapted to receive a resilient packing or sealing ring R which, as will be explained more in detail, is expandable inwardly from an open position (FIGS. 1 and 3) to a sealing or closed position (FIG. 4) by means of pressure in an inflatable bag A. As will be explained more in detail hereinafter, because of the particular construction of the blowout preventer B of this invention, the bore of the preventer is adapted to be fully open so that well tools or a pipe such as the tubing string T are adapted to normally pass therethrough without any contact by the preventer, but in the event of blowout conditions, the ring R may be moved inwardly so that its inner bore is reduced in diameter to seal the annular space around the tubing string T or such other object as may be in the bore of the preventer B to thereby control the well and prevent a blowout thereof. I

The blowout preventer B is adapted to be connected in a well casing or pipe in the usual manner and for this purpose, the lower part of the housing H has an annular flange 10 with a plurality of bolt holes 10a therethrough for connecting to a corresponding flange on a section of well casing or pipe therebelow. The housing H is preferably provided with a removable annular housing section 12 which is threaded or is otherwise connected to the rest of the housing by relatively coarse threads 1211. Such removable housing section 12 preferably has a plurality of threaded holes 12b into which suitable studs may be threaded from a flange or other connector on a portion of the well casing there above. As will be more evident hereinafter, the inner and outer diameters of the removable housing section 12 correspond substantially with the inner and outer diameters of the resilient packing or sealing ring R to facilitate the assembly and disassembly of the resilient ring R and other parts therewith. The housing H has a recess 15, a portion of which is preferably formed by the housing section 12 for receiving the resilient ring R and the inflatable bag A, as well as other parts as will be further explained. As can be seen in FIG. 1, the inner bore 16 of the housing H is preferably substantially coincident with the inner bore 17 of the resilient ring R, and also the inner bore 12c of the removable housing section 12. Also, such bores 16, 17 and are preferably at least as large as the inner bore of the well casing to which the housing H is attached. Thus, a fully open bore is provided through the blowout preventer B so that drill bits, reamers, and other large diameter tools may pass freely therethrough when the preventer is in the open position shown in FIGS. 1 and 3.

The resilient ring R is formed of rubber or other suitable resilient material, and in the preferred embodiment of the invention, a plurality of upper wedges 20 and lower wedges 22 are secured to such resilient ring R. In fact, each of the upper wedges 20 is preferably connected to one of the lower wedges 22 immediately therebelow by a connector section 23, all of which are formed of steel or other similar material. Thus, the upper wedge members 20 and the lower wedge members 22 are preferably the same in number and in arrangement and they move together with the rubber or other resilient material of the ring R during the contraction and expansion of the ring R, as will be more evident hereinafter.

The upper wedge members 20 are illustrated in the preferred form in FIGS. 3 and 4, wherein it can be seen that such wedge members or wedges 20 are circumferentially disposed in a circular arrangement with spaces 24 therebetween. As will be more evident hereinafter, such spaces 24 between the upper wedges 20 are reduced in width as the wedges 20 move radially inwardly during the contraction of the resilient ring R due to the pressure within the inflatable bag A. Thus, as seen in FIG. 4, the spaces 24 have been reduced in width since the resilient member R has moved into sealing engagement with the external surface of the tubing string T. Such wedges 20 may thus move inwardly radially until the spaces 24 are completely closed, or the inward radial movement thereof is limited or stopped by some other means such as stop pins 25 (FIGS. 1 and 2) or the pipe or tool which is contacted by the resilient member R. Each of the pins 25 is adapted to move within a slot 12d which may be annular or which may be made in a plurality of separate slots, one for each of the stop pins 25. In any event, when the stop pins 25 engage the inner wall l2e of the slot 12d, the inward radial movement of the members 20 is stopped to thereby prevent extreme eccentric positions of the ring R and to control the inward radial movement or contraction of the resilient ring R, which may be desirable for larger radius blowout preventers.

The lower wedges 22 are preferably arranged in the identical manner to the wedges 20 since they are interconnected by the connecting sections 23. Likewise, the lower wedges 22 may have stop pins 27 therewith which move in one or more slots 15a until they contact the inner wall 151; to stop or limit the inward movement of the lower wedges 22 for the same purpose as the limit on the upper wedges 20.

The upper wedges are interconnected to prevent twisting or turning thereof and also to minimize the extrusion of the rubber or other resilient material of the sealing ring 17 by means of a lug 20a which is connected to or is integral with each of the wedge members 20 and which extends into a recess or channel 20b on the adjacent wedge 20. As best seen in FIG. 2, the recess 20b and the interconnecting lug 20a are formed below the actual wedge shaped portion of the wedge member 20, but in any event, the adjacent wedges 20 are interconnected by means of the interfitting of the lugs 20a in the recesses or grooves 20b of the adjacent wedges 20.

A similar interconnecting means is provided for the wedges 22 and it includes an interconnecting lug 22a on one side of each of the wedge members 22 which fits into a recess or groove 22b on the other side of such wedge members 22. Preferably, the lugs 220 are on the opposite sides of the wedge members 22 from the lugs 20a as shown in FIG. 2 so that regardless of which one of two adjacent wedges moves inwardly, the other is likewise moved. It is to be noted that the inner surfaces of the wedges 20 and 22 are substantially coincidental with the inner bore 17 of the resilient ring R so that such steel or other metal of the wedge members 20 and 22 serve as retainer or confining members for the resilient ring R to prevent its substantial extrusion upwardly or downwardly, respectively, when forced inwardly to the sealing or packing position in contact with the tubing string T or other object within the bore of the pre venter B.

The inflatable bag A is preferably made of rubber or other resilient material and it is annular in construction with an inner chamber 30 which is closed except for an inlet opening 30a formed at an insert 31 which is integral with the bag A. An inflating tube 32 (FIG. 1) extends through an opening in the housing H and is disposed within the insert 31, with the outer end of the tube 32 having a connector 33 or other suitable means for connection to a source of air, other gas, or other fluid under pressure (not shown). Such air or other fluid is applied under pressure within the chamber 30 for inflating same to exert an inward compressive force on the resilient ring R when it is desired to move same to a closed or packing position such as shown in FIG. 4. To limit the extrusion of the inner wall of the bag A so as to facilitate the urging of the ring R inwardly when the pressure is developed within the chamber 30 of the bag A without extruding the rubber or other material of the bag A into spaces between the'wedge members 20, 22 and the lugs 20a, 22a, a plurality of substantially vertical ribs or strips 40 are molded or are otherwise embedded in the rubber of the bag A for spanning the vertical distance from the upper wedges to the lower wedges 22. Such ribs or strips 40 are preferably formed of steel or other similar material which is rigid enough to serve as a means to prevent the outward extrusion of the rubber or other material of the resilient ring R when it is subjected to the pressure in the bag A. A typical disposition of the ribs or strips 40 for accomplishing the purposes of the invention as heretofore described is illustrated in FIGS. 3 and 4 in particular.

As best seen in FIG. 1, the height of the blowout preventer B of this invention is relatively short as compared to the height of the normal I-Iydril" type of blowout preventer. The height of the inflatable bag A is approximately equal to the height of the resilient ring R, including the wedges 20 and 22 therewith.

In the operation or use of the blowout preventer B of this invention, the parts are initially assembled with the housing section 12 removed so that the bag A is positioned in the recess 15 as shown in FIG. 1. The connection to the gas or inlet tube 32 is accomplished in any known or convenient manner so as to connect the source of air, gas or other fluid pressure to the chamber 30 on the inside of the bag A. The resilient ring R with the wedges 22 and 20 as an assembly are then inserted inwardly of the bag A and the pins 27 are positioned in the slot or slots 16a. Thereafter, the removable housing section 12 is threadedly connected to the rest of the housing H to position the pins 25 in the annular slot 12. With the threaded type of connection illustrated in FIG. 1, the slot 12d would have to be annular to permit the relative rotation of the housing section 12 with respect to the rest of the housing I-I. However, if the connection between the removable housing section 12 and the rest of the housing H is modified, it will be appreciated that the shape of the slot 12d may be modified so long as the pins 25 are movable therein until they hit the stop surface 12e as previously explained.

Normally, the blowout preventer B is in the position illustrated in FIGS. 1-3, but when it is desired to actuate the blowout preventer B to close the annular space around the tubing string T or other object which extends longitudinally in the bore of the blowout preventer B, the fluid pressure within the chamber 30 of the bag A is increased to thereby cause an inward movement or contraction of the inner bore 17 of the resilient ring R until it contacts the external surface of the tubing string T or other object. The wedge members 20 and 22 move with the resilient ring R inwardly from the position shown in FIG. 3 to the position shown in Flg. 4, thereby retaining the rubber ring R above and below while the ribs or strips 40 on the inner wall of the bag A confine the external surface of the ring R. Thus, in the final sealing position of FIG. 4, the ring R is substantially confined on all sides so as to prevent its extrusion to any extent and to assure a firm seal with the external surface of the tubing T or other object within the bore of the blowout preventer B. In some instances, the blowout preventer B may be actually closed so that the opening through the bore 17 closes in the event there is no tubing string T or other object within the bore of the blowout preventer B.

One of the significant features of this invention resides in the fact that the seal ring R which is the principal part subjected to wear during usage may be readily removed, together with the confining wedges and parts therewith, from the blowout preventer for replacement or other purposes. Thus, the present invention provides as a subcombination a replaceable wear assembly which includes the seal ring R and the confining members to allow closure, and prevent extrusion of the rubber or other material of the ring R, over a range of sizes of pipe or other objects engaged thereby, or in the open bore when no object is present therein.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape, and materials as well as in the details of the illustrated construction may be made without departing from the spirit of the invention.

I claim:

1. An annular blowout preventer, comprising:

a housing having a longitudinal bore therethrough and an annular lateral recess communicating with said bore;

a resilient packing ring disposed in said recess and having an inner bore which is at least as large as said longitudinal bore of said housing;

a plurality of upper retainer wedges secured to the upper part of said packing ring and engageable with the upper inner wall of said recess;

a plurality of lower retainer wedges secured to the lower part of said resilient ring and engageable with the lower inner wall of said recess;

a resilient inflatable bag disposed in said recess outwardly of said resilient ring and adapted to be inflated for exerting an inward force on said ring to reduce the diameter of the inner bore thereof for sealing engagement with itself or with an object extending longitudinally in said bore;

said upper retainer wedges being spaced circumferentially from each other when said ring is in the fully open bore position and being adapted to move inwardly with said ring as it is urged inwardly by the pressure in said inflatable bag to gradually reduce the spaces between the upper;

said lower retainer wedges being spaced circumferentially from each other-when said ring is in the fully open bore position and being adapted to move inwardly with said ring as it is urged inwardly by the pressure in said inflatable bag to gradually reduce the spaces between the lower wedges;

upper wedge interlocking means interlocking the adjacent upper wedges together as they move radially inwardly and outwardly for preventing twisting and turning of the upper wedges relative to each other and for providing substantially uniform radial contraction;

lower wedge interlocking means interlocking the adjacent lower wedges together as they move radially inwardly and outwardly for preventing twisting and turning of the lower wedges relative to each other; and

retainer means circumferentially disposed and embedded near the inner annular surface of said inflatable bag for limiting inward extrusion of the material of said bag into any spaces between said wedges and said wedge interlocking means.

2. The structure set forth in claim 1, wherein:

said retainer means is substantially vertical, rigid, and

circumferentially disposed.

3. The structure set forth in claim 2, wherein:

said retainer means includes a plurality of members, each of which is rigid and substantially vertically disposed. 

1. An annular blowout preventer, comprising: a housing having a longitudinal bore therethrough and an annular lateral recess communicating with said bore; a resilient packing ring disposed in said recess and having an inner bore which is at least as large as said longitudinal bore of said housing; a plurality of upper retainer wedges secured to the upper part of said packing ring and engageable with the upper inner wall of said recess; a plurality of lower retainer wedges secured to the lower part of said resilient ring and engageable with the lower inner wall of said recess; a resilient inflatable bag disposed in said recess outwardly of said resilient ring and adapted to be inflated for exerting an inward force on said ring to reduce the diameter of the inner bore thereof for sealing engagement with itself or with an object extending longitudinally in said bore; said upper retainer wedges being spaced circumferentially from each other when said ring is in the fully open bore position and being adapted to move inwardly with said ring as it is urged inwardly by the pressure in said inflatable bag to gradually reduce the spaces between the upper; said lower retainer wedges being spaced circumferentially from each other when said ring is in the fully open bore position and being adapted to move inwardly with said ring as it is urged inwardly by the pressure in said inflatable bag to gradually reduce the spaces between the lower wedges; upper wedge interlocking means interlocking the adjacent upper wedges together as they move radially inwardly and outwardly for preventing twisting and turning of the upper wedges relative to each other and for providing substantially uniform radial contraction; lower wedge interlocking means interlocking the adjacent lower wedges together as they move radially inwardly and outwardly for preventing twisting and turning of the lower wedges relative to each other; and retainer means circumferentially disposed and embedded near the inner annular surface of said inflatable bag for limiting inward extrusion of the material of said bag into any spaces between said wedges and said wedge interlocking means.
 2. The structure set forth in claim 1, wherein: saId retainer means is substantially vertical, rigid, and circumferentially disposed.
 3. The structure set forth in claim 2, wherein: said retainer means includes a plurality of members, each of which is rigid and substantially vertically disposed. 